[eric242340]

Guys, I think you are jumping to conclusions without looking at the obvious first. Missfire on cylinder 1 and 4? The air mass meter could not cause only 1 and 4 to missfire. If it were the Mass meter the missfires would be random and not specific to one or two cylinders hence the smooth enging test on DAS.

Fuel injectors, yes it could be on 1 and 4.

HT leads from the coils to the plugs on 1 and 4 it could be and is a common fault on these engines.

Catalitic convertor is not something that is going to cause cylinder specific missfires. Nor will the oxygen sensors.

An air leak yes it could be on 1 and 4? I dont think so because air leaks tend to affect one or all the cylinders and not two specifically. It would be a large coincidence to find this.

Coils yes possibly, but two at the same time rarely.

So my advice is to change the HT leads on 1 and 4 first and see how it goes from there and they are not expensive, however an air mass meter is in comparrison.

The coolant temperature thing may be a problem but is easy to check as 43sqd has already advised and this too will not cause two specific cylinders to missfire, hope this all makes sense.